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COLUMN ONE : Something New Under the Sun : Astronomers hope exotic tools will help them probe beneath the massive fireball's surface. Big Bear is a hot spot for research into our nearest but oft-neglected star.

November 11, 1995|K.C. COLE | TIMES SCIENCE WRITER

As night snuffs out the day over Big Bear Lake in the San Bernardino Mountains, the sky lights up with familiar mythological creatures: in the canopy of constellations it's easy to find Draco the Dragon, the Greek hero Perseus, and Ursa Major, the Big Bear (better known as the Big Dipper).

But to the astronomers in the observatory on a spit of land in the middle of the lake, these denizens of the deep sky are collectively dismissed as "the dark side."

These astronomers start their day at dawn, when the nighttime astronomers go to sleep. And they study one special star.

It is a star that spews streamers of electrically charged particles that extend for millions of miles into space. Its nuclear furnace converts the mass of two dozen ocean liners into pure energy every second.

"It's my favorite star," said Caltech astrophysicist Hal Zirin, who directs the Big Bear Observatory.

The star, of course, is our sun.

As it turns out, our own personal star poses mysteries as deep as any black hole and as quizzical as any quasar.

That situation may be about to change. Equipped with exotic new technology, scientists are embarking on an unprecedented exploration of the sun.

The centerpiece is a six-station global network that will listen to the sun as it sings out in 10 million different tones. Appropriately known as GONG (for Global Oscillation Network Group), the system will allow scientists to probe under the sun's surface for the first time. Just as sonograms use sound to peer inside a mother's womb at a developing baby, sound waves bounding around inside the sun reveal a great deal about the star's internal structure. The difference is that the solar sound waves are generated by the acoustics of the sun itself.

"Until now, it's as if we were geologists and all we've had is a shovel; we could just poke at the dirt," said GONG project director John Leibacher of the National Solar Observatory in Tucson. "What we'd like to know is: What the devil is going on underneath?"

Another new eye on the sun is the joint U.S.-European satellite Ulysses, which recently completed its first pass over the star's north pole--the first time it has been viewed from that vantage point. "Solar physics is really leaping ahead," said Edward Smith, project scientist for the Ulysses satellite for the Jet Propulsion Laboratory in Pasadena.

The sun is quiet now, at the so-called solar minimum. Its next cycle of fireworks isn't due until 2001.

"We've seen the simple sun," Smith said. When Ulysses comes back for a second pass in six years [from its orbit around the solar system], "we'll see it when it's in its most complicated state. And that should be fascinating."

And when the sun acts up, Earth can take a direct hit.

In April, 1984, as then-President Ronald Reagan was flying to China on Air Force One, the star flared up with such force that it scrambled radio signals and silenced the Great Communicator for hours. In March, 1989, it had blacked out Quebec for days.

Both the glowing curtains of colored lights that drape the northern skies as auroras and the magnetic storms that knock out power systems are clear evidence of solar effects. Some solar physicists even think that cycles of solar activity might affect overall global climate. A prolonged cold snap that froze much of Europe for more than 50 years in the 17th Century coincided with an almost complete absence of sunspots.


Learning about the sun will help scientists know more about things that lie far beyond our solar system. "The sun is not the only star in the sky," Smith said. In fact, it's a fairly average star, of average mass and brightness, middle-aged at 5 billion years. With a better idea of what powers the sun, astrophysicists will better understand the life cycles of all stars--information that is critical to pinning down the age and size of the universe.

But many solar astronomers say their star is being neglected for more exotic strangers in galaxies far away. Their references to "the dark side" convey a certain bitterness. "There is no glory in daytime astronomy, and yet our lives depend on it," Zirin said. "It's crazy."

Ever since Galileo turned his homemade telescope skyward and saw that the star was not a perfectly smooth heavenly sphere, people have wondered about its unaccountable variability. For example, the sun periodically breaks out in spots. These dark splotches appear where the magnetic fields are tied up in knots, and they are often associated with solar flare-ups. But no one knows exactly how the spots relate to flares--which makes it impossible to predict when blasts of electrified particles are heading toward Earth. To unprepared astronauts, such outbursts could be fatal.


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